do not generate labels for empty dashboard graphs

Avoid a JS error if a line graph has no points. This is mostly useful
for collideoscope where we only want to show one line.

1 files changed, 3 insertions, 0 deletions

diff --git a/web/js/dashboard.js b/web/js/dashboard.js
index 82b5e6188..318e64c76 100644
--- a/web/js/dashboard.js
+++ b/web/js/dashboard.js
@@ -30,6 +30,9 @@ $(function(){
 
         var lasty = 0;
         $.each(chart.config.data.datasets, function(datasetIndex, dataset){
+            if (dataset.data.length == 0) {
+                return;
+            }
             var $label = $('.label[data-datasetIndex="' + datasetIndex + '"]', $parent);
             var latestPoint = chart.getDatasetMeta(datasetIndex).data[ dataset.data.length - 1 ];
             var y = latestPoint._model.y;